Some yearn for departed Custos, some revere Rufus, some swear by (though, in moments of deepest puzzlement, sometimes possibly at) the inventive Paul. But plainly the best-loved of Guardian crossword setters, more than half a century since his first concoction appeared, is Araucaria, less well known as the Reverend John Graham MBE. The first of the great crossword compilers called himself Torquemada, the second Ximenes – each taking his name from an agent of the inquisition. John Graham settled for the more benign alias Araucaria, taken from the tree known in Britain as the monkey puzzle. That is not to say he is averse to inducing a sense of helplessness in his clientele. The French call the tree "the monkey's despair", and it's one mark of the perfect crossword that the solver will at some point despair of being able to finish it. There are critics who bemoan his failure to obey strict Ximenean rules. Yet even they must honour the astonishing ingenuity with which he furnishes clues that tempt you in one direction when quite another is wanted; serves up idiosyncratic treats like his alphabetical crosswords, where you have to fill the answers into an unnumbered grid; or somehow gathers so many composers or cattle or cricket grounds into one puzzle that his customers gasp in wonder. All the fruits of an erudition that ranges easily from Bach through to Lady Gaga, from Aristotle to Keith Flett. These qualities are happily undiminished as he celebrates his 90th birthday today.